Reclosing torques of large induction motors with stator trapped flux

Large induction motors are subjected to high transient torques following the rapid reconnection of the supply. The paper shows that these torques have oscillatory components with speed dependent frequencies. These components may result in high torsional torques if the supply is reconnected at an unfavorable instant; when the frequency of one of the torque components coincides with the natural torsional frequency. However, this high torque can be avoided by the proper choice of the reclosing instant